As a typical example exhibiting semiconductor properties, Group 14 elements such as silicon and germanium are represented. Particularly, silicon has been utilized in almost all semiconductor devices and recognized as a material supporting the basis of the electronics industry because of its wide availability, easiness of processing, excellent semiconductor properties, and easiness of controlling properties.
Recent finding of semiconductor properties in oxides, in particular oxides of Group 13 elements such as indium and gallium, has motivated intensive research and development. As a typical example of oxides exhibiting semiconductor properties (hereinafter, referred to as an oxide semiconductor), indium-gallium oxide (IGO), indium-gallium-zinc oxide (IGZO), and the like have been known. Intensive research in recent years has realized commercialization of display devices having transistors including these oxide semiconductors as a semiconductor element. Additionally, as exemplarily disclosed in Japanese patent application publication No. 2015-225104, international publication No. 2015-031037, and United States patent application publication 2010/0182223, a semiconductor device in which both a transistor having a silicon-including semiconductor (hereinafter, referred to as a silicon semiconductor) and a transistor having an oxide semiconductor are incorporated has been developed.